sapenc.c

Go to the documentation of this file.

/*
 * Session Announcement Protocol (RFC 2974) muxer
 * Copyright (c) 2010 Martin Storsjo
 *
 * This file is part of FFmpeg.
 *
 * FFmpeg is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public
 * License as published by the Free Software Foundation; either
 * version 2.1 of the License, or (at your option) any later version.
 *
 * FFmpeg is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public
 * License along with FFmpeg; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
 */

#include "avformat.h"
#include "libavutil/parseutils.h"
#include "libavutil/random_seed.h"
#include "libavutil/avstring.h"
#include "libavutil/dict.h"
#include "libavutil/intreadwrite.h"
#include "libavutil/time.h"
#include "internal.h"
#include "network.h"
#include "os_support.h"
#include "rtpenc_chain.h"
#include "url.h"

struct SAPState {
    uint8_t    *ann;
    int         ann_size;
    URLContext *ann_fd;
    int64_t     last_time;
};

static int sap_write_close(AVFormatContext *s)
{
    struct SAPState *sap = s->priv_data;
    int i;

    for (i = 0; i < s->nb_streams; i++) {
        AVFormatContext *rtpctx = s->streams[i]->priv_data;
        if (!rtpctx)
            continue;
        av_write_trailer(rtpctx);
        avio_closep(&rtpctx->pb);
        avformat_free_context(rtpctx);
        s->streams[i]->priv_data = NULL;
    }

    if (sap->last_time && sap->ann && sap->ann_fd) {
        sap->ann[0] |= 4; /* Session deletion*/
        ffurl_write(sap->ann_fd, sap->ann, sap->ann_size);
    }

    av_freep(&sap->ann);
    ffurl_closep(&sap->ann_fd);
    ff_network_close();
    return 0;
}

static int sap_write_header(AVFormatContext *s)
{
    struct SAPState *sap = s->priv_data;
    char host[1024], path[1024], url[1024], announce_addr[50] = "";
    char *option_list;
    int port = 9875, base_port = 5004, i, pos = 0, same_port = 0, ttl = 255;
    AVFormatContext **contexts = NULL;
    int ret = 0;
    struct sockaddr_storage localaddr;
    socklen_t addrlen = sizeof(localaddr);
    int udp_fd;
    AVDictionaryEntry* title = av_dict_get(s->metadata, "title", NULL, 0);

    if (!ff_network_init())
        return AVERROR(EIO);

    /* extract hostname and port */
    av_url_split(NULL, 0, NULL, 0, host, sizeof(host), &base_port,
                 path, sizeof(path), s->url);
    if (base_port < 0)
        base_port = 5004;

    /* search for options */
    option_list = strrchr(path, '?');
    if (option_list) {
        char buf[50];
        if (av_find_info_tag(buf, sizeof(buf), "announce_port", option_list)) {
            port = strtol(buf, NULL, 10);
        }
        if (av_find_info_tag(buf, sizeof(buf), "same_port", option_list)) {
            same_port = strtol(buf, NULL, 10);
        }
        if (av_find_info_tag(buf, sizeof(buf), "ttl", option_list)) {
            ttl = strtol(buf, NULL, 10);
        }
        if (av_find_info_tag(buf, sizeof(buf), "announce_addr", option_list)) {
            av_strlcpy(announce_addr, buf, sizeof(announce_addr));
        }
    }

    if (!announce_addr[0]) {
        struct addrinfo hints = { 0 }, *ai = NULL;
        hints.ai_family = AF_UNSPEC;
        if (getaddrinfo(host, NULL, &hints, &ai)) {
            av_log(s, AV_LOG_ERROR, "Unable to resolve %s\n", host);
            ret = AVERROR(EIO);
            goto fail;
        }
        if (ai->ai_family == AF_INET) {
            /* Also known as sap.mcast.net */
            av_strlcpy(announce_addr, "224.2.127.254", sizeof(announce_addr));
#if HAVE_STRUCT_SOCKADDR_IN6
        } else if (ai->ai_family == AF_INET6) {
            /* With IPv6, you can use the same destination in many different
             * multicast subnets, to choose how far you want it routed.
             * This one is intended to be routed globally. */
            av_strlcpy(announce_addr, "ff0e::2:7ffe", sizeof(announce_addr));
#endif
        } else {
            freeaddrinfo(ai);
            av_log(s, AV_LOG_ERROR, "Host %s resolved to unsupported "
                                    "address family\n", host);
            ret = AVERROR(EIO);
            goto fail;
        }
        freeaddrinfo(ai);
    }

    contexts = av_mallocz_array(s->nb_streams, sizeof(AVFormatContext*));
    if (!contexts) {
        ret = AVERROR(ENOMEM);
        goto fail;
    }

    if (s->start_time_realtime == 0  ||  s->start_time_realtime == AV_NOPTS_VALUE)
        s->start_time_realtime = av_gettime();
    for (i = 0; i < s->nb_streams; i++) {
        URLContext *fd;
        char *new_url;

        ff_url_join(url, sizeof(url), "rtp", NULL, host, base_port,
                    "?ttl=%d", ttl);
        if (!same_port)
            base_port += 2;
        ret = ffurl_open_whitelist(&fd, url, AVIO_FLAG_WRITE,
                                   &s->interrupt_callback, NULL,
                                   s->protocol_whitelist, s->protocol_blacklist, NULL);
        if (ret) {
            ret = AVERROR(EIO);
            goto fail;
        }
        ret = ff_rtp_chain_mux_open(&contexts[i], s, s->streams[i], fd, 0, i);
        if (ret < 0)
            goto fail;
        s->streams[i]->priv_data = contexts[i];
        s->streams[i]->time_base = contexts[i]->streams[0]->time_base;
        new_url = av_strdup(url);
        if (!new_url) {
            ret = AVERROR(ENOMEM);
            goto fail;
        }
        ff_format_set_url(contexts[i], new_url);
    }

    if (s->nb_streams > 0 && title)
        av_dict_set(&contexts[0]->metadata, "title", title->value, 0);

    ff_url_join(url, sizeof(url), "udp", NULL, announce_addr, port,
                "?ttl=%d&connect=1", ttl);
    ret = ffurl_open_whitelist(&sap->ann_fd, url, AVIO_FLAG_WRITE,
                               &s->interrupt_callback, NULL,
                               s->protocol_whitelist, s->protocol_blacklist, NULL);
    if (ret) {
        ret = AVERROR(EIO);
        goto fail;
    }

    udp_fd = ffurl_get_file_handle(sap->ann_fd);
    if (getsockname(udp_fd, (struct sockaddr*) &localaddr, &addrlen)) {
        ret = AVERROR(EIO);
        goto fail;
    }
    if (localaddr.ss_family != AF_INET
#if HAVE_STRUCT_SOCKADDR_IN6
        && localaddr.ss_family != AF_INET6
#endif
        ) {
        av_log(s, AV_LOG_ERROR, "Unsupported protocol family\n");
        ret = AVERROR(EIO);
        goto fail;
    }
    sap->ann_size = 8192;
    sap->ann = av_mallocz(sap->ann_size);
    if (!sap->ann) {
        ret = AVERROR(EIO);
        goto fail;
    }
    sap->ann[pos] = (1 << 5);
#if HAVE_STRUCT_SOCKADDR_IN6
    if (localaddr.ss_family == AF_INET6)
        sap->ann[pos] |= 0x10;
#endif
    pos++;
    sap->ann[pos++] = 0; /* Authentication length */
    AV_WB16(&sap->ann[pos], av_get_random_seed());
    pos += 2;
    if (localaddr.ss_family == AF_INET) {
        memcpy(&sap->ann[pos], &((struct sockaddr_in*)&localaddr)->sin_addr,
               sizeof(struct in_addr));
        pos += sizeof(struct in_addr);
#if HAVE_STRUCT_SOCKADDR_IN6
    } else {
        memcpy(&sap->ann[pos], &((struct sockaddr_in6*)&localaddr)->sin6_addr,
               sizeof(struct in6_addr));
        pos += sizeof(struct in6_addr);
#endif
    }

    av_strlcpy(&sap->ann[pos], "application/sdp", sap->ann_size - pos);
    pos += strlen(&sap->ann[pos]) + 1;

    if (av_sdp_create(contexts, s->nb_streams, &sap->ann[pos],
                      sap->ann_size - pos)) {
        ret = AVERROR_INVALIDDATA;
        goto fail;
    }
    av_freep(&contexts);
    av_log(s, AV_LOG_VERBOSE, "SDP:\n%s\n", &sap->ann[pos]);
    pos += strlen(&sap->ann[pos]);
    sap->ann_size = pos;

    if (sap->ann_size > sap->ann_fd->max_packet_size) {
        av_log(s, AV_LOG_ERROR, "Announcement too large to send in one "
                                "packet\n");
        goto fail;
    }

    return 0;

fail:
    av_free(contexts);
    sap_write_close(s);
    return ret;
}

static int sap_write_packet(AVFormatContext *s, AVPacket *pkt)
{
    AVFormatContext *rtpctx;
    struct SAPState *sap = s->priv_data;
    int64_t now = av_gettime_relative();

    if (!sap->last_time || now - sap->last_time > 5000000) {
        int ret = ffurl_write(sap->ann_fd, sap->ann, sap->ann_size);
        /* Don't abort even if we get "Destination unreachable" */
        if (ret < 0 && ret != AVERROR(ECONNREFUSED))
            return ret;
        sap->last_time = now;
    }
    rtpctx = s->streams[pkt->stream_index]->priv_data;
    return ff_write_chained(rtpctx, 0, pkt, s, 0);
}

AVOutputFormat ff_sap_muxer = {
    .name              = "sap",
    .long_name         = NULL_IF_CONFIG_SMALL("SAP output"),
    .priv_data_size    = sizeof(struct SAPState),
    .audio_codec       = AV_CODEC_ID_AAC,
    .video_codec       = AV_CODEC_ID_MPEG4,
    .write_header      = sap_write_header,
    .write_packet      = sap_write_packet,
    .write_trailer     = sap_write_close,
    .flags             = AVFMT_NOFILE | AVFMT_GLOBALHEADER,
};